The Sample Size Calculator determines the number of completed surveys needed to get the desired confidence interval for a survey.

Confidence Level tells you how certain you can be that the sample estimate will contain the value of the population. It is expressed as a percentage, that is, 95% confidence level means you can be 95% certain; the 99% confidence level means you can be 99% certain.  Most researchers choose the 95% confidence level.

Confidence Interval (Margin of Error) is the plus-or-minus figure reported in opinion poll results. The most common interval used is +/- 5%.

For your convenience, The Myers Group has created a Sample Size Calculator for your own personal use in Excel format.  Simply right click on the icon or link, and click "Save Target As..."

Sample Size Calculator